The present invention relates to a DA converter, a data line driving circuit, an electro-optical device, a driving method thereof, and an electronic apparatus.
As an electro-optical device replacing a liquid crystal display device, a great attention is paid to a device including an organic light emitting diode (OLED) element. The OLED element acts as a diode from an electrical point of view. From an optical point of view, the OLED element emits light when it is forwardly biased, and the amount of light emission is increased in proportion to the increase of a forward bias current.
An electro-optical device having OLED elements arranged in the form of a matrix includes a plurality of scan lines, a plurality of data lines, and pixel circuits provided respectively at intersections of the scan lines and the data lines. Each pixel circuit serves to store a value of current supplied from a respective data line and supply a driving current to a respective OLED element such that the respective OLED element has the stored value of current.
Such an electro-optical device includes a data line driving circuit for supplying current signals according to gray-scale levels to be represented for the plurality data lines. The data line driving circuit typically includes a plurality of current mode digital to analog (DA) converters corresponding to the plurality of data lines. There is a case where the current mode DA converters, each including a plurality of current sources using current mirror circuits, select output signals of the current sources based on a digital signal value and output the selected output signals as current signals (for example, see Patent Document 1).
In addition, since the data lines are accompanied with stray capacitance, there is a case where pre-charge voltages are supplied to the data lines before current signals are supplied to the data lines (for example, see Patent Document 2). In this case, the data line driving circuit is required to include a special circuit for supplying a pre-charge voltage, in addition to the current mode DA converter.
[Patent Document 1] Japanese Unexamined Patent Application Publication No. 2000-293245.
[Patent Document 2] Japanese Unexamined Patent Application Publication No. 2003-44002.